LMR14050: Kindly suggest Supply Voltage and Current to choose the SMPS/Power Adapter.

LMR14050SDDA is 4v to 40V input voltage with 5A loading capacity. so 14V to 19V DC in should be ok in SCH. 

Hi Elena,

Thank you for the information.

I want to know the possible input ranges for the given load(Power Tree). Kindly advise for individual query.

1. As per the schematic and Power tree, For 12V output will work fine with input supply range 13V to 40V? What will be the required input supply Current for LMR14050SDDA?

2. How to calculate the LMR14050SDDA load current? because we using two different load voltage. one is 12V at 700mA load and second is 3.3V at 1A load. So, what will be the actual load for  LMR14050SDDA?

Thanks and regards,

Naveen K

hi, NAveen,

LMR14050SDDA could handle no higher than 40V input voltage source , the current is cal by Vout 12V *Iloading/Vin (like 14V to 19V) , 

LMR14050SDDA load current should be all the current together, like you have a 700mA +LDO3.3V*1A/12V, remember to leave some margin for it 。 max current for LMR14050SDDA is 5A. 

Elena

hi, Naveen,

1, please use worse case at 14V min input voltage. for safe you could set a current limit like 1.5A or 1A.

2, yes, you are right ,

3, yes, also right.

Elena

Hi Elena,

Thank you for the information and appreciate for quick response.

1. We will suggest our product user to Supply, Min= 14V @ 1.1A, Typ= 24V @ 0.55A and Max= 40V @ 0.35A, is this right?

2. Any Input voltages ranges from 14V-40V, 1A will not affect the Output Voltage/current and Regulator efficiency will not degradable and not heat up right?

3. If we don't have 12V load, we can directly convert from 14V-40V to 3.3V, right? LMR14050SDDA will not heat-up & not affect to reliability, right?

4. As we told, 3.3V source connected to CC3220MODSFMOBR, TLV9002IDR, SN65HVD73, 4-LED(source from CC3220). Kindly advice, how to calculate the current consumption of the above IC's. Please find the below schematic for CC3220MODSF and advise the maximum current consumption.

Thanks and regards,

Naveen K

hi, Naveen,

I will give you a feedback on workday. Thank you.

Elena

hi, Naveen,

1, yes, 

2,yes

3, better not to directly use, it have U6 in your first SCH, change 12V to 3,3V. this is more stable and safe for 3,3V to drive CC3220MODSFMOBR and others.

4, I am not familiar with CC3220MODSFMOBR ,please open a new ticket to the right product team.

Elena

Hi Elena,

Thank you for the information.

Could you please advice, whether LMR14050SDDA input need any Filter to protect from Noise/Surge or not?

Thanks and regards,

Naveen K

hi, Naveen,

a fuse and a diode should be good for protect over current. EMI filter is helpful to improved for EMI but it may not be a necessary part , which will increase the board size and cost .

Elena

Hi Elena,

Thank you for the information and appreciate your quick response.

Diode is for reverse Protection? If not, What is the need and from where to connect? What kind of Diode?

Thanks and regards,

Naveen K

yes, I means  for reverse Protection

Hi Elena,

Thank you for your advice.

Presently we using MOSFET for reverse protection. Any diode advantage over MOSFET except diode need 0.7V voltage drop and diode cost is cheaper.

1. In which case we need consider Diode and in which cases we need to consider MOSFET?

2. Also advice, in which cases we need to consider EMI filter and in which cases we can neglect EMI filter?

Thanks and regards,

Naveen K

hi, Naveen,

I have checked from your SCH , it already have a protect circuit, F1, Q6, D7 ,  and filter C53,C54, L4, the design is good and no other need.

Elena

Hi Elena,

Thank you for the information.

Yes some products having, but in some other product we are eliminated Fuse and Filter due to size/price constraints. Only Q1,D7(reverse Protection) using. Kindly advise below query, so that we can think to add or neglect for existing product or for new product, based on your advice.  

1. In which case we need to consider Diode and in which cases we need to consider MOSFET for reverse protection?

2. Also advice, in which cases we need to consider EMI filter and in which cases we can neglect EMI filter?

Thanks and regards,

Naveen K

Hi Naveen,

The diode power loss is P_loss=Vf*Iin, diode junction temp can be estimated or measured under worst operating condition, normally Schottky diode is used for lower Vf, if Tj is higher than Tj_max (say 150C) in worst case, then you need to use MOSFET.  another concern is low Vin condition, if you require tight output regulation when Vin drop close to Vout, then you'd better to use MOSFET for lower Vf

You need to design EMI filter if the product has EMC requirement.  one EMI filter for whole system is OK, no need dedicated one for LMR140X0 converter, but you can add one bead on input to filter out high freq noise early.

B R

Andy 

Hi Andy,

Thank you for the information.

Bead should be on before the filter or instead of filter we need to use Bead?

Only primary input side filter is sufficient and Filter is not required on Output side like LMR140X0 out, 5V out, 3.3V output side, right?

Could you please advice how to calculate Inductor, Capacitor values on the filter?

Also advice, how i can choose the Bead value?

Thanks and regards,

Naveen K

Hi Naveen,

Pls download the Application Note for how to design EMI filter.

AN-2162 Simple Success With Conducted EMI From DCDC Converters

B R

Andy

Hi Andy,

Thank you for the information and appreciate your fast response.

Suggested application note explains how to design the filter and value. Kindly suggest,

Only primary input side filter is sufficient and Filter is not required on Output side like LMR140X0 out, 5V out, 3.3V output side, right?

Bead should be on before the filter or instead of filter we need to use Bead? Also advice, how i can choose the Bead value?

Thanks and regards,

Naveen K

Hi Andy,

Thank you for the information.

Last Query,  LMR14050 having load of 0.975 A, required input is 24V,0.55A. What will be the current rating for the Fuse?

We can use either SMD PTC Resettable Fuses (MF-MSMF050-2) or Radial (RKEF050), Both types are fine, right? Any recommendation?

Thanks and regards,

Naveen K

Hi Naveen,

Sorry I'm not familiar with the fuse.

I take a quick look, MF-MSMF050-2 can NOT be used:

1. voltage rating only 16V

2.  Trip current decreased at high temp

B R

Andy 

Hi Andy,

Thank you for the information.

I hope we can use if we go with higher voltage like 40V on MF-MSMF050/40X.

Just i want to know Trip current should be 1x or 1.5x or 2x of LMR14050 input current.

Thanks and regards,

Naveen K

Hi Naveen,

Pls check the input current at worst case(Minimum Vin, heavy load, high ambient temp), then select trip current at high temp 1.5X of the input current in worst case.

B R

Andy

Hi Elena and Andy,

Thank you for the information and well Appreciated your support.

Thanks and regards,

Naveen K